Synthesis and characterization of copolythiophene

Copolythiophenes (Co‐PTs), poly(3‐hexylthiophene‐co‐3‐thiophene carboxylic acid) (P3HT‐TCa), poly(3‐hexyloxylthiophene‐co‐3‐thiophene carboxylic acid) (P3HOT‐TCa), and poly(3‐phenylthiophene‐co‐3‐thiophene carboxylic acid) (P3PhT‐TCa), were synthesized by chemical oxidized polymerization to investigate the effect of copolymerization on the properties of polythiophenes (PTs). Gel permeation chromatography showed that the molecular weight (MW) of Co‐PT was lower than that of homopolythiophene. Fourier transform infrared (FTIR) spectra indicated that the copolymerization was successful between the monomers. The λ_max of Co‐PTs gave a “blue shift” in ultraviolet‐visible (UV‐VIS) spectra. Photoluminescence (PL) spectra showed that the PL intensity of Co‐PT became weaker than that of homopolythiophene and the disappearance of PL had been observed in P3HOT‐TCa. The thermal stability of Co‐PT was influenced by the carboxyl for its low decomposition temperature. Furthermore, the copolymerization between multi‐wall carbon nanotube containing thiophene ring (MWNT‐Th) and 3‐hexyloxylthiphene could also take place successfully. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

An ontological engineering approach for automating inspection and quarantine at airports

Customs and quarantine departments are applying information systems to automate their inspection processes and improve their inspection efficiency and accuracy. The product codes from the Harmonized System (HS codes) are the essential elements of the system's integration, automation and intelligence. The identified HS codes are well-accepted and precise product references used by customs authorities, to match applicable policies to the products being inspected and taxed. Domain ontology for importing and exporting industry can be used to acquire HS codes for given products, and is a prerequisite for an integrated and intelligent automated inspection system. The authors have proposed and implemented an importing and exporting domain ontology. The ontology is composed of an integrated and comprehensive knowledge base derived from static dictionaries and the HS specification, and dynamic processing data. Based on this ontology, a reasoning engine is developed to generate HS codes intelligently for the given product names. Information systems can use the engine to get HS codes for submitted products and find applicable policies automatically. The ontology and the engine have been implemented in a Java-based platform and published as a HS Web service. In this paper, knowledge structure, reasoning mechanism and implementation details for the domain ontology and reasoning engine are presented. A test bed in the application environment has been conducted and experimental results have been obtained. The ontology and the service have the potential to be widely used by authorities and international traders of importing and exporting industry around the world.     

共享主存多SIMD结构及编译技术研究

目前多媒体应用已经成为各种运算平台的主要应用类型。随着多媒体应用的多样性和复杂性,共享主存多SIMD结构逐渐成为主从多核结构中多媒体加速部件的首要选择。总结了目前共享主存多SIMD结构的特征,同时深入分析了共享主存多SIMD编译优化的主要问题以及相关编译技术。     

A new approach to pointer analysis for assignments

Pointer analysis is a technique to identify at copile-time the potential values of the pointer expressions in a program,which promises significant benefits for optimzing and parallelizing complilers.In this paper,a new approach to pointer analysis for assignments is presented.In this approach,assignments are classified into three categories:pointer assignments,structure(union)assignents and normal assignments which don‘t affect the point-to information.Pointer analyses for these three kinds of assignments respectively make up the integrated algorithm.When analyzing a pointer assigemtn.a new method called expression expansion is used to calculate both the left targets and the right targets.The integration of recursive data structure analysis into pointer analysis is a significant originality of this paper,which uniforms the pointer analysis for heap variables and the pointer analysis for stack variables.This algorithm is implemented in Agassiz,an analyzing tool for C programs developed by Institute of Parallel Processing,Fudan University,Its accuracy and effectiveness are illustrated by experimental data.     

微网友好接入的柔性变流器并网接口控制方法

针对微网友好接入对高性能并网接口的需求,提出了一种新型的柔性变流器并网接口。为了使该并网接口有效地工作,给出了基于瞬时无功功率理论的电流检测方法,深入研究了柔性变流器并网接口直流侧电压和定无功功率控制方法;此外,基于加权电流反馈的思想,提出了谐波和不对称电流综合补偿的滞环电流控制方法。最后应用Matlab/Simulink进行了仿真,仿真结果进一步验证了使用所提并网接口与控制策略实现微网友好接入的有效性和可行性。     

Dielectric,ferroelectric, and piezoelectric properties in potassium sodium niobate ceramics with rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries

A new phase boundary with rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries is designed in (K_0.48Na_0.52)NbO₃ by adding Bi_0.5(Na_0.7K_0.2Li_0.1)_0.5ZrO₃ (BNKLZ), where Zr⁴⁺ and (BNKL)²⁺ are respectively used to improve the temperature of a rhombohedral phase and to decrease the temperature of an orthorhombic–tetragonal phase coexistence. These ceramics endure several continuous phase transitions with increasing BNKLZ content, i.e., an orthorhombic phase (0≤x<0.03), orthorhombic–tetragonal phases (x=0.03), orthorhombic–tetragonal and rhombohedral–orthorhombic (O–T and R–O) phase existence (0.03<x≤0.05), a rhombohedral phase (0.05<x≤0.07). The ceramics with O–T and R–O have a better piezoelectric behavior as compared with other phases because of more polarization states, enhanced ε_r and P_r, and a dense microstructure. Moreover, piezoelectric properties could be further optimized by modifying their sintering and poling temperatures. As a result, the construction of O–T and R–O phase coexistence benefits the improvement of piezoelectric properties in KNN-based ceramics.     

AZ31镁合金薄带铸轧温度场的数值模拟

借助ANSYS软件下的Fluent模块模拟了AZ31镁合金铸轧区的温度场,研究了AZ31镁合金薄带铸轧时不同工艺参数下铸轧区的三维温度场的分布,分析了温度场的分布对薄带铸轧过程稳定性的影响。通过对比分析模拟结果,给出在所选取范围内最佳工艺参数是,浇注温度为853K,铸轧速度为9m/min,冷却水流速为3m/s。     

Ni含量对Mg-Gd合金组织的影响

采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)以及X射线衍射分析(XRD)等手段,研究了Ni含量对Mg98-xGd2Nix(摩尔分数,下同,x=0,0.5,1.0)合金组织的影响。结果表明,铸态下,不含Ni的Mg98Gd2合金组织由初生树枝状α-Mg和分布在树枝间的少量共晶第二相Mg5Gd相组成;添加0.5%的Ni后,合金中Mg5Gd相消失而出现第二相X-Mg12GdNi相,其面积分数达到27%;Ni含量增加至1%时,合金相组成未发生变化,X相面积分数增至42%。在500℃固溶热处理时,随着固溶时间延长,Mg98Gd2合金中第二相Mg5Gd相逐渐溶入基体,而固溶时间达到20h,含Ni的Mg97.5Gd2Ni0.5和Mg97Gd2Ni1合金中第二相X相未发生明显溶解,且基体α-Mg的二次枝晶臂未见明显长大,表明X相具有优良的热稳定性并能有效抑制基体α-Mg的长大。     

大庆油田聚合物驱油工业化推广应用研究

对大庆油田聚合物驱油工业化推广应用的驱油效果进行分析研究以后，认为聚合物的驱油效果除了与已经研究过的聚合物的分子量、溶液浓度、用量、注入速度和注入方式等工艺技术条件有关外，还与地质条件和含油饱和度等因素有关。目前，大庆油田聚合物驱油已经取得采收率２．０１％的明显效果，预测最终采收率可提高１３．０％左右。     

计及紧急直流功率支援的扰动后稳态频率预测算法

提出了一种计及紧急直流功率支援情况下,能同时考虑直流两侧电网频率响应的扰动后稳态频率预测算法。该算法对系统发电机调速器方程、负荷静态模型方程、直流输电系统传输功率方程和系统网络方程进行了线性化处理,同时考虑紧急直流功率支援,推导了两区域交直流系统扰动后稳态频率预测方程,可以直接快速地计算出扰动后各区域的稳态频率和使其中一个区域稳态频率恢复到设定值时的直流功率支援量。对一个典型的两区域交直流并联系统进行了仿真分析,仿真结果表明所提算法具有较高的精度和较快的计算速度,证明了算法的适用性和有效性,具有与紧急频率控制相配合并在线应用的前景。